Re: [PATCH] board: amlogic: fix buffler overflow in serial & usid read

On Tue, Mar 19, 2024 at 03:53:24PM +0100, Neil Armstrong wrote:
> While meson_sm_read_efuse() doesn't overflow, the string is not
> zero terminated and env_set() will buffer overflow and add random
> characters to environment.
> 

In the Linux kernel we would give this a CVE because it's information
disclosure bug...

> Signed-off-by: Neil Armstrong <[email protected]>
> ---
>  board/amlogic/jethub-j80/jethub-j80.c | 6 ++++--
>  board/amlogic/p200/p200.c             | 3 ++-
>  board/amlogic/p201/p201.c             | 3 ++-
>  board/amlogic/p212/p212.c             | 3 ++-
>  board/amlogic/q200/q200.c             | 3 ++-
>  5 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/board/amlogic/jethub-j80/jethub-j80.c b/board/amlogic/jethub-j80/jethub-j80.c
> index 185880de13..d10492cc46 100644
> --- a/board/amlogic/jethub-j80/jethub-j80.c
> +++ b/board/amlogic/jethub-j80/jethub-j80.c
> @@ -28,8 +28,8 @@
>  int misc_init_r(void)
>  {
>  	u8 mac_addr[EFUSE_MAC_SIZE];
           ^^^^^^^^^^^^^^^^^^^^^^^^

This one is also a problem.  You can't pass non-terminated strings to
eth_env_set_enetaddr().  We call strlen() on it in either hsearch_r() or
env_get_from_linear().

All the other functions had a mac_addr[] issue as well.

Btw, this kind of bug is a good candidate for a static checker warning.
I can create a Smatch check for this.  It would probably be easier in
Coccinelle even, but I'm the Smatch maintainer.

regards,
dan carpenter


> -	char serial[EFUSE_SN_SIZE];
> -	char usid[EFUSE_USID_SIZE];
> +	char serial[EFUSE_SN_SIZE + 1];
> +	char usid[EFUSE_USID_SIZE + 1];
>  	ssize_t len;
>  	unsigned int adcval;
>  	int ret;
> @@ -46,6 +46,7 @@ int misc_init_r(void)
>  	if (!env_get("serial")) {
>  		len = meson_sm_read_efuse(EFUSE_SN_OFFSET, serial,
>  					  EFUSE_SN_SIZE);
> +		serial[len] = '\0';
>  		if (len == EFUSE_SN_SIZE)
>  			env_set("serial", serial);